Allergies and asthma have become highly prevalent in the western world. Allergies and asthma now affect about one out of every four Americans, which is three times the number of people suffering from diabetes. Moreover, the prevalence of allergies and asthma has seen a significant increase since about 1960 as reported, for example, by Waltraud Eder, et al., “The asthma epidemic,” The New England Journal of Medicine 355, no. 21 (Nov. 23, 2006), pages 2226-2235. Allergies and asthma are two examples of ailments which result from weakened or stressed immune systems.
Health problems associated with weakened or stressed immune systems are frequently exacerbated by the failure of individuals to understand the status of their immune system or factors influencing the status of their immune system. This lack of understanding is discussed, for example, by M Wills-Karp, et al. “The germless theory of allergic disease; revisiting the hygiene hypothesis,” Nature Reviews. Immunology 1, no. 1 (October 2001), pages 69-75, and Claire-Anne Siegrist, “Public health: Autoimmune diseases after adolescent or adult immunization: What should we expect?,” CMAJ: Canadian Medical Association Journal 177, no. 11 (Nov. 20, 2007), pages 1352-1354.
Treatment of chronic diseases and ailments is also adversely affected by lack of insight into the status of an individual's immune system. For example, when pursuing allergen specific immunotherapy the lack of insight into the individual's immune system increases risks associated with the treatment or necessitates increased medical supervision and subsequent costs. Such adverse effects are discussed, for example, by Rudolf Valenta, “The future of antigen-specific immunotherapy of allergy,” National Review of Immunology 2, no. 6 (June 2002), pages 446-453, and Mark Larche, et al., “Immunological mechanisms of allergen specific immunotherapy,” National Review of Immunology 6, no. 10 (October 2006), pages 761-771.
In a clinical setting, the reaction of the immune system of an individual's environment or exposure to a substance can be inferred by analysis of various biomarkers such as chemokines and cytokines as reported by K Gelhar, et al., “Monitoring allergen immunotherapy of pollen-allergic patients: the ratio of allergen specific IgG4 to IgG1 correlates with clinical outcome,” Clinical and Experimental Allergy: Journal of the British Society for Allergy and Clinical Immunology 29, no. 4 (April 1999), pages 497-506.
While detection of the levels of chemokines and cytokines in a biological sample has traditionally required large pieces of equipment, recent advances have enabled diagnostic tests that can be performed at the point of care of an individual, such as at the bedside of a patient, at a care provider location, or at the home of the patient. The promise of such diagnostic tests is described, for example, by Leroy Hood et al., “Systems Biology and New Technologies Enable Predictive and Preventative Medicine,” Science 306, no. 5696 (Oct. 22, 2004): 640-643. Depending upon the particular diagnostic test, the substance tested may be human body fluids such as blood, serum, saliva, biological cells, urine, or other biomolecules. Diagnostic tests are not, however, limited to biomolecules since testing may be further desired on consumables such as milk, baby food, or water.
Many diagnostic testing devices incorporate affinity based sensors which are considered to be the state-of-the-art in detection of biomarkers. Affinity based sensors function according to a “key-lock” principal in which a molecule with very high association factor to the marker of interest is used for detection. For example, a pregnancy test kit may incorporate a monoclonal antibody specific to a β-subunit of hCG (βhCG). The antibody is conjugated with a tag, e.g., gold, latex, or fluorophore, which is used for detection. If the targeted molecule binds with the conjugated antibody, the tagged key-lock pair will be detectable such as by a visible test line.
ELISA plates and microarrays (e.g., Nucleic Acid, peptide, and protein) incorporate a similar principal. FIG. 1 depicts an ELISA assay 10 wherein antibodies 12 are immobilized on a substrate 14. The substrate 14 may be positioned within a well (not shown). A blocker 16 is provided to cover the surface of the substrate around the antibody 12. In a typical ELISA assay, a sample 18 is then added to the well in which the primary antibody 12 is immobilized. Next, the sample is incubated for some time. During incubation, the blocker 16 prevents the molecules of interest in the sample from binding to the surface of the substrate 14 in order to avoid false binding. During incubation, some of the molecules of interest 18 become bound with some of the antibodies 12 as depicted in FIG. 2. After incubation, the remaining sample is washed to remove the unbound primary antibodies 18.
Subsequently, a secondary antibody 20 with a bound label 22 is added to the well, incubated, and washed resulting in the configuration of FIG. 3. As depicted in FIG. 3, the labeled secondary antibodies 20 are bound to the molecules of interest 18 that are in turn bound to the antibodies 12. Accordingly, the number of labels 22 bound by the antibodies 20 to the antigen 18 is proportional to the concentration of the target antigen. Depending on the label used, the number of labels can be finally detected using colorimetry, amperometry, magnetometry, voltammetry, luminescence, or fluorescence detection. Other label-free antibody processes such as surface plasmon resonance may alternatively be used.
Accordingly, there is a need for a system and method that allow self monitoring of an individual's immune system. A further need exists for a system including a portable device which can be used to provide insight into the immune system of an individual. It would be further beneficial if such a device could be worn by the individual.